I can understand your hesitation and also your preoccupation with all three devices: they definitely offer up different experiences and have excellent benefits to owning that specific device.
Though Samsung may be iffy with updates, I'd say you are in the best position to either hold onto that or the Pixel 2 XL. Not that I don't love the Essential Phone (I do!); but Google has promised two years' warranty on their phones and is always pushing updates. The Essential 2 is apparently on the way though, so it looks like they're gonna be going strong!
But yeah, I'd say either the Samsung or Pixel phones would be the best choices for longevity.
Thanks.. I've had the opportunity to use many of the top Android devices: OP5T, note 8, essential and pixel 2xl.I can say with reassurance that I'm down to either the pixel 2xl or note 8 and am swayed towards the p2xl at this point.